Phosphino compounds, compositions and methods of destroying arachnids



rates 3,052,596 PHOSPI-WO COMPOUNDS, COMPOSITIONS AND METHODS F DESTROYING ARACHNIDS Joseph W. Baker and John P. Chupp, Kirkwoorl, and

Peter E. Newallis, Crestwood, Mo., assignors to Monsanto Chemical Company, St. Louis, Mo., a corporation of Delaware No Drawing. Filed Mar. 17, 1960, Ser. No. 15,547

19 Claims. ((11. 167-22) This invention relates to new and useful phosphino compounds and to methods of making same. Additionally this invention relates to acaricidal (or miticidal) compositions containing the new phosphino compounds as an active ingredient.

The new compounds of this invention while broadly termed phosphino compounds can be conveniently termed phosphinothioates and can be represented by the structure XI av R\% OR" RI OR!!! wherein R, R', R" and R are like or unlike lower alkyl (ie an alkyl radical containing up to carbon atoms); and wherein X and X are chalkogens of atomic weight less than 40 (Le. sulfur or oxygen). It is preferred that R, R, R and R be like or unlike alkyl radicals containing from 1 to 3 carbon atoms (i.e. methyl, ethyl, npropyl or isopropyl).

Compounds of this invention wherein X is sulfur in the foregoing structure can be prepared by reacting in an anhydrous system a phosphinoic halide of the structure l -halogen wherein R, R and X have the aforedescribed significance and wherein the term halogen means a halogen having an atomic number above 9 but not higher than 35 (i.e. chlorine or bromine, preferably chlorine) with a substantially equimolecular amount of a salt (i.e. ammonium or alkali metal such as sodium, potassium or lithium) of a phosphorodithioic acid of the structure RIIIO wherein R and R'" have the aforedescribed significance in the presence of an inert organic liquid or solvent (e.g. acetone, butanone, dioxane, benzene, toluene, xylene, etc.). While a wide range of reaction temperatures can be employed provided the system is fluid (ie a temperature above the freezing point of the system and up to and including the boiling point of the system) it is preferred to employ a reaction temperature in the range of from 20 C. to 120 C. Alternatively phosphinothioates of this invention of the foregoing structure wherein X is sulfur can be prepared under the foregoing conditions by reacting in an anhydrous system a phosphoric halide of the structure P-halogen RIHO with a substantially equirnolecular amount of a salt (ammonium or alkali metal such as sodium, potassium or lithium) of a phosphinothioic acid of the structure P-SH 3,652,596 Patented Sept; 4, 1962 & wherein R, R, R", R, X and halogen have the aforementioned significance.

As illustrative of the phosphinothioates of this invention are As illustrative of the preparation of the compounds of this invention is the following:

Example I To a suitable reaction vessel equipped with a thermometer, agitator and reflux condenser is charged 22.3 parts by weight (substantially 0.11 mole) of ammonium salt of 0,0-diethyl phosphorodithioic acid, 12.8 parts by weight (substantially 0.10 mole) of dimethylphosphinothioic chloride, and approximately 50 parts by weight of acetone. The charge is heated at the reflux temperature for 4 hours, cooled to room temperature and filtered. The filtrate is then subjected to vacuum distillation to remove the acetone. The residue is then taken up with methylene chloride and the organic solution washed first with 3% aqueous sodium carbonate and then with water. The s0-washed organic solution is then subjected to vacuum distillation to remove the methylene chloride. The residue, a yellow liquid, is S-(diethoxyphosphinothioyl) dimethylphosphinodithioate which is soluble in benzene and acetone but insoluble in water.

Employing the procedure of Example I but replacing dimethylphosphinothioic chloride with an equimolecular amount of dimethylphosphinoic chloride there is obtained S-(diethoxyphosphinothioyl) dimethylphosphinothioate a liquid which is soluble in benzene but insoluble in water.

Employing the procedure of Example I but replacing the ammonium salt of 0,0-diethyl phosphorodithioic acid with an equimolecular amount of the sodium salt of dimethylphosphinodithioic acid and replacing dimethyl phosphinothioic chloride with an equirnolecular amount of 0,0-dimethyl phosphoric chloride there is obtained oily S-(dirnethoxyphosphinyl) dimethylphosphinodithioate which is soluble in benzene but insoluble in water.

Example IV Employing the procedure of Example I but replacing the ammonium salt of 0,0-diethyl phosphorodithioic acid with an equi-molecular amount of the ammonium salt of dimethylphosphinodithioic acid and replacing dimethylphosphinothioic chloride with an equimolecular amount of 0,0-dimethyl phosphorothioic chloride there is obtained S-(dimethoxyphosphino-thioyl) dimethylphosphinodithioate which liquid is soluble in benzene but insoluble in water.

In the process of this invention any inert organic liquid or mixture of inert organic liquids can be used provided at least one of the reactants is soluble therein. The methods by which the phosphinothioates of this invention are isolated will vary slightly with the reactants employed and the product produced. Further purification by selective solvent extraction or by absorptive agents such as activated carbon or clays can precede the removal of the inert organic liquid or solvent. Additionally an inert organic solvent can be added to and in the purification by absorptive agents. However, the product is generally satisfactory for acaricidal (or miticidal) purposes without further purification.

The phosphinothioates of this invention are eifective against a wide variety of arachnid pests. As illustrative of the activity but not limitative thereof is the following:

One gram of S-(diethoxyphosphinothioyl) dimethylphosphin-odithioate was dissolved in sufficient acetone to make a concentrated solution thereof. Approximately 0.1 cc. of sorbitan monolaurate polyoxyethylene derivative (a commercial water-soluble non-ionic emulsifying agent) is then mixed with the concentrate. To this mixture and with agitation is added suflicient water to provide an aqueous emulsion having a concentration of 0.013% by weight of S-(diethoxyphosphinothioyl) dimethylphosphinodithioate. Thereupon lima bean plant leaves infested with the two-spotted spider mite, T etranychus telarius (L.), are dipped in the aqueous emulsion, withdrawn, and set aside for observation. At the end of 48 hours a 100% kill of the mobile stage of the mite was noted. Similar results against the mobile stage of the same mite are obtained employing S-(dimethoxyphosphinothioyl) dimethylphosphinodithioate.

Systemic activity was also observed against a wide variety of arachnids. For example against the twospotted spider mite, Tetranychus telarius (L.), a 90% kill was observed employing S-(diethoxyphosphinothioyl) dimethylphosphinodithioate at a concentration of 0.01% by weight.

Although the phosphinothioates of this invention are useful per se in controlling a wide variety of arachnid pests, it is preferable that they be supplied to the pests or to the environment of the pest or pests in a dispersed form in a suitable extending agent.

In the instant specification and appended claims it is to be understood that the term dispersed is used in its widest possible sense. When it is said that the phosphinothioates of this invention are dispersed, it means that the particles of the phosphinothioates of this invention may be molecular in size and held in true solution in a suitable organic solvent. It means further, that the particles may be colloidal in size and distributed throughout a liquid phase in the form. of suspensions or emulsions or in the form of particles held in suspension by wetting agents. It also includes particles which are distributed in a semi-solid viscous carrier such as petrolatum or soap or other ointment base in which they may be actually dissolved in the semi-solid or held in suspension in the semisolid With the aid of suitable wetting or emulsifying agents. The term dispersed also means that the particles may be mixed with and distributed throughout a solid carrier providing a mixture in particulate form, e.g. pellets, granules, powders, or dusts. The term dispersed also includes mixtures which are suitable for use as aerosols including solutions, suspensions, or emulsions of the phosphinothioates of this invention in a carrier such as dichlorodifiuoromethane and like fluorochloroalkanes 4 which boil below room temperature at atmospheric pressure.

In the instant specification and appended claims it is to be understood that the expression extending agent includes any and all of those substances in which the phosphinothioates of this invention are dispersed. It includes, therefore, the solvents of a true solution, the liquid phase of suspensions, emulsions or aerosols, the semisolid carrier of ointments and the solid phase of particulate solids, e.g. pellets, granules, dusts and powders.

The exact concentration of the phosphinothioates of this invention employed in combatting or controlling arachnid pests can vary considerably provided the required dos-age (i.e. toxic or lethal amount) thereof is supplied to the pests or to the environment of the pests. When the extending agent is a liquid or mixture of liquids (e.g. as in solutions, suspensions, emulsions or aerosols) the concentration of the phosphinothioate employed to supply the desired dosage generally Will be in the range of 0.001 to 50 percent by weight. When the extending agent is a semi-solid or solid, the concentration of the phosphinothioate employed to supply the desired dosage generally will be in the range of 0.1 to 25 percent by weight. From a practical point of view, the manufacturer must supply the agriculturist with a low-cost concentrate or spray base or particulate solid base in such form that, by merely mixing with water or solid extender (e.g. powdered clay or talc) or other low-cost material available to the agriculturist at the point of use, he will have an easily prepared acaricidal spray or particulate solid. In such a concentrate composition, the phosphinothioate generally will be present in a concentration of 5 to 95 percent by weight, the residue being any one or more of the well-known acaricidal adju-vants, such as the various surface-active agents (e.g., detergents, a soap or other emulsifying or wetting agent, surface-active clays), solvents, diluents, carrier media, adhesives, spreading agents, humectants, and the like.

There are a large number of organic Liquids which can be used for the preparation of solutions, suspensions, or emulsions, of the phosphinothioates of this invention. For example, iso propyl ether, acetone, methyl ethyl ketone, dioxane, cyclohex-anone, carbon tetrachloride, ethylene dichloride, tetrachloroethane, hexane, heptane and like higher liquid alrkanes, hydrogenated naphthalenes, solvent naphtha, benzene, toluene, xylene, petroleum fractions (e.g. those boiling almost entirely under 400 F at atmospheric pressure and having a flash point above about F., particularly kerosene), mineral oils having an unsulfonatable residue above about 80 percent and preferably above about percent. In those instances wherein there may be concern about the phytotoxicity of the organic liquid extending agent a portion of same can be replaced by such low molecular weight aliphatic hydrocarbons as dipentene, diisobutylene, propylene trimer, and the like or suitable polar organic liquids such as the aliphatic ethers and the aliphatic ketones containing not more than about 10 carbon atoms as exemplified by acetone, methyl ethyl ketone, d-iisobutyl ketone, dioxane, isopropyl ether, and the like. In certain instances, it is advantageous to employ a mixture of organic liquids as the extending agent.

When the phosphinothioates of this invention are to be supplied to the arachnid pests or to the environment of the pests as aerosols, it is convenient to dissolve them in a suitable solvent and disperse the resulting solution in dichlorodifluoromethane or like chlorofiuoroalkane which boils below room temperature at atmospheric pressure.

The phosphinothioates of this invention are preferably supplied to the arachnid pests or to the environment of the arachnid pests in the form of emulsions or suspensions. Emulsions or suspensions "are prepared by dispersing the phosphinothioates of this invention either per se or in the form of an organic solution thereof in water with the aid of a water-soluble surfactant. 'Ilhe term surfactant as employed here and in the appended claims is used as in volume II of Schwartz, Perry and Bertchs Surface Active Agents and Detergents (1958, Interscience Publishers, Inc., New York), in place of the expression emulsifying agent" to connote generically the various emulsifying agents, dispersing agents, wetting agents and spreading agents, that are adapted to be admixed with the active ingredients in the water vehicle or carrier in which they are insoluble through lowering the surface tension of the water (see also Fre-ar, Chemistry of Insecticides, Fungicides and Herbicides, second edition, page 280). These surfactants include the well known capillary-active substances which may be anion-active (or anionic), cation-active (or cationic) or non-ionizing (or non-ionic) which are described in detail in volumes I and II of Schwartz, Perry and Berchs Surface Active Agents and Detergents (1958, Interscience Publishers, Inc., New York), and also in the November 1947 issue of Chemical Industries (pages 811 842) in an article entitled Synthetic Detergents, by John W. McCutcheon, and also in the July, August, September and October 1952 issues of Soap and Sanitary Chemicals under the title Synthetic Detergents. The disclosures of these articles with respect to surfactants, i.e. the anion-active, cation-active and non-ionizing capillary active substance, are incorporated in this specification by reference in order to avoid unnecessary enlargement of this specification. The preferred surfactants are the water-soluble anionic surface active agents and watersoluble non-ionic surface active agents set forth in US. 2,846,398 (issued August 5, 1958). in general it is preferred that a mixture of water-soluble anionic and watersoluble non-ionic surfactants be employed.

The phosphinothioates of this invention can be dispersed by suitable methods (e.g. tumbling or grinding) in solid extending agents either of organic or inorganic nature and supplied to the arachnid pest environment in particulate form. Such solid materials include, for example, tricalcium phosphate, calcium carbonate, kaolin, bole, kieselguhr, talc, bentonite, fullers earth, pyrophillite, diatomaceous earth, calcined magnesia, volcanic ash, sulfur and the like inorganic solid materials, and include, for example, such materials of organic nature as powdered cork, powdered wood, and powdered walnut shells. The preferred solid carriers are the adsorbent clays, e.g. bentonite. These mixtures can be used for acaricidal purposes in the dry form, or, by addition of water-soluble surfactants or wetting agents the dry particulate solids can be rendered wettable by water so as to obtain stable aqueous dispersions or suspensions .suitable for use as sprayable compositions.

For special purposes the phosphinothioates of this invention can be dispersed in a semi-solid extending agent such as petrolaturn or soap (e.g., sodium stearate or oleate or palrnitate or mixtures thereof) with or without the aid of solubility promoters and/ or surfactants or dispersing agents.

In all of the forms described above the dispersions can be provided ready for use in combatting arachnid pests or they can be provided in a concentrated form suitable for mixing with or dispersing in other extending agents. As illustrative of a particularly useful concentrate is an intimate mixture of phosphinothioates of this invention with a water-soluble surfactant which lowers the surface tension of water in the weight proportions of 0.1 to 15 parts of surfactant with sufficient of the phosphinothioate of this invention to make 100 parts by weight. Such a concentrate is particularly adapted to be made into a spray for combatting various forms of arachnid pests (particularly mites) by the addition of water thereto. As illustrative of such a concentrate is an intimate mixture of 95 parts by weight of S-(diethoxyphosphinothioyl) dimethylphosphinodithioate and 5 parts by weight of a water-soluble non-ionic surfactant such as the poly oxyethylene derivative of sorbitan monolaurate.

Another useful concentrate adapted to be made into 6 a spray for combatting arachnid pests (particularly mites) is a solution (preferably as concentrated as possible) of a phosphinothioate of this invention in an organic solvent therefor. The said liquid concentrate preferably contains dissolved therein a minor amount (e.g., 0.5 to 10 percent by weight of the Weight of the new acan'cidal agent) of a surfactant (or emulsifying agent), which surfactant is also water-soluble. As illustrative of such a concentrate is a solution of S-(dirnethoxyphosphinothioyl) dimethylphosphinothioate in benzene which solution contains dissolved therein a water-soluble alkylaryl sulfonate anionic surfactant.

Of the surfactants aforementioned in preparing the various emulsifiable, wettable or dispersible compositions or concentrates of this invention, the anionic and nonionic surfactants are preferred. Of the anionic surfactants, the particularly preferred are the well-known wator-soluble alkylaryl sulfonates, e.g. sodium decylbenzene sulfonate and sodium dodecylbenzene sulfonate. Of the non-ionic surfactants, the particularly preferred are the water-soluble polyoxyethylene derivatives of alkylphenols (particularly isooctylphenol) and the water soluble polyoxyethylene derivatives of the mono-higher fatty acid e8- ters of sorbitan.

In all of the various dispersions described hereinbefore for acaricidal or miticidal purposes, the active in gredient can be one or more of the compounds of this invention. The compounds of this invention can also be advantageously employed in combination with other pesticides, including, for example, nematocides, bactericides, fungicides, and herbicides. In this manner it is possible to obtain mixtures which are effective against a wide variety of pests and other forms of noxious life.

In controlling or combatting arachnid pests the phosphinothioates of this invention per se or compositions comprising same are supplied to the arachnid pests or to their environment in a lethal or toxic amount. This can be done by dispersing the new acaricidal agent or acaricidal composition comprising same in, on or over an infested environment or in or over an environment the arachnid pests frequent, e.g. agricultural soil or other growth media or other media infested with the arachnid pests or attractable to the pests for habitational or sustenance or propagational purposes, in any conventional fashion which permits contact between the arachnid pests and the phosphinothioates of this invention. Such dispersing can be brought about by applying the new phosphinothioates per se or sprays or particulate solid compositions containing same to a surface infested with the arachnid pests or attractable to the pests, as for example, the surface of an agricultural soil or other media such as the above ground surface of plants by any of the conventional methods, e.g. power dusters, boom and hand Sprayers, and spray clusters. Also for sub-surface application such dispersing can be carried out by simply mixing the new acaricidal agent per se or acaricidal spray or particulate solid composition comprising same with the infested environment or with the environment the arachnid pests frequent, or by employing a liquid carrier for the new acaricidal agent to accomplish sub-surface penetration and impregnation thereof therein.

While this invention has been described with respect to certain embodiments, it is to be understood that it is not so limited and that variations and modifications thereof obvious to those skilled in the art can be made without departing from the spirit or scope thereof.

What is claimed is:

1. Phosphinothioates of the structure R X X OR \ll 11/ P-SP R! OR!!! wherein -R, R, R and R are lower alkyl radicals and wherein X and X are chalkogens of atomic weight less than 40.

2. S (diethoxyphosphinothioyl) dimethylphosphinodithioate.

3. S (diethoxyphosphinothioyl) dimethylphosphinothioate.

4. S (dimethoxyphosphinyl) thioate.

5. S (dimethoxyphosphinothioyl) dimethylphosphinodithioate.

6. Phosphinothioates of the structure dimethylphosphinodi- IL -halogen wherein R, R' and X have the same significance as above and wherein the term halogen means a halogen of atomic number above 9 but not higher than 35 with a substantially equirnolecular amount of a salt selected from the class consisting of ammonium and alkali metal salts of a phosphorodithioic acid of the structure Rllo\fi P-SH RIIIO wherein R" and R'" have the same significance as above in the presence of an inert organic liquid.

8. The method of making phosphinothioates of the structure wherein R, R, R" and R' are lower alkyl radicals and wherein X is a chalkogen of atomic weight less than 40 which comprises reacting in an anhydrous system a phosphoroic halide of the structure P-halogen RIIIO wherein R", R" and X have the same significance as above and wherein the term halogen means a halogen having an atomic number above 9 but not higher than 35 with a substantially equimolecular amount of a salt selected from the class consisting of ammonium and alkali metal salts of a phosphinodithioic acid of the structure i -SH wherein R and R have the same significance as above in the presence of an inert organic liquid.

'9. An acaricidal composition comprising a compound of claim 1 dispersed in an extending agent.

10. An acaricidal composition comprising a compound of claim 1 dispersed in an extending agent, the composition containing 0.1 to 25 percent by weight of said compound of claim 1, the extending agent being selected from the group consisting of solid and semi-solid extending agents.

11. An acaricidal composition comprising a compound of claim 1 dispersed in a liquid extending agent, the composition containing 0.001 to 50 percent by weight of said compound of claim 1.

12. An acaricidal composition comprising a compound of claim 6 dispersed in an adsorbent clay, the composition containing 0.1 to 25 percent by weight of said compound of claim 6.

13. An acaricidal concentrate comprising a compound of claim 6 and an insecticidal adjuvant, said concentrate containing from 5 to '95 percent by weight of the compound of claim 6.

14. An acaricidal concentrate comprising a compound of claim 1 dispersed in an organic solvent therefor and having dissolved therein a minor amount of a surfactant, said concentrate forming an emulsion with water upon agitation therewith.

15. An acaricidal concentrate adapted to he made into a sprayable composition 'by the addition of water comprising a compound of claim 6 in admixture with a water-soluble surfactant in the weight proportion of 0.1 to 15 parts of surfactant and sufiicient of said compound of claim 6 to make parts by weight.

16. The method of controlling arachnids which comprises contacting the arachnids with a toxic amount of a compound of claim 1.

17. The method of controlling arachnids which comprises contacting the arachnids with a toxic amount of a compound of claim 6.

18. The method of controlling arachnids which comprises contacting the arachnids with a toxic amount of a compound of claim 3.

19. The method for protection of plants against arachnid attack which comprises applying to the plant an acaricidal amount of at least one compound of claim 1.

References Cited in the file of this patent UNITED STATES PATENTS 2,630,450 Harman Mar. 3, 1953 2,787,629 Coover Apr. 2, 1957 2,909,559 Lanham Oct. 20, 1959 2,920,993 'Fairchild Ian. 12, 1960 2,928,862 Willard Mar. 15, 1960 2,929,832 Schrader Mar. 22, 1960 2,930,730 Scott Mar. 29, 1960 

1. PHOSPHINOTHIOATES OF THE STRUCTURE 